1. Field of the Invention
The present invention relates to a nozzle beam for descaling or cooling metal strand material, particularly rolling stock. The nozzle beam includes an inlet for the product treatment liquid and an additional inlet for a device cooling liquid and an outlet for the device cooling liquid and a switching member for the outlet for opening and closing the device cooling liquid outlet.
2. Description of the Related Art
DE-OS 34 33 712 discloses a cooling water outlet in a device for producing a water curtain for cooling sheets or strips which are moved through the water curtain, wherein the cooling water outlet includes a water box with a slot-shaped nozzle extending over the width of the strand material transversely of the direction of movement of the sheets or strips. A siphon pipe is provided laterally next to the slot-shaped nozzle for discharging the continuously supplied cooling water, wherein the inlet opening of the siphon pipe is arranged below the inlet opening of the slot-shaped nozzle and its siphon and discharge opening are arranged below the discharge opening of the slot-shaped nozzle. A device of this kind has the disadvantage that the cooling water continues to be conducted through the nozzle beam and the cooling water is applied to and cools the rolling stock even when only the cooling device itself is to be cooled or protected and the rolling stock no longer requires cooling.
In the past, two separate chambers were required for the functions xe2x80x9cproduct treatmentxe2x80x9d and xe2x80x9ccooling of the devicexe2x80x9d or at least a switching member with a separate energy supply in the case of an electrical control and a corresponding signal processing means were required.
The cooling water is usually required for protecting the cooling device itself when it is xe2x80x9cout of operationxe2x80x9d against excessive heating and any resulting damage. For changing between xe2x80x9cout of operationxe2x80x9d and xe2x80x9cin operationxe2x80x9d the above-mentioned switching member with an appropriate control command is necessary in order to switch on or off the cooling water required for the cooling device.
It is the primary object of the present invention to provide a nozzle beam in which, during the time that the supply of product treatment liquid is switched off, the necessary cooling of the treatment or cooling device itself is maintained while the strand product travels through the nozzle beam.
In accordance with the present invention, in the nozzle beam of the above-described type, the switching member is automatically switchable through a device cooling liquid pressure which controls the state of operation.
As a result of the configuration according to the present invention, the treatment liquid outlet is automatically closed or later again opened on the basis of a pressure in the treatment liquid which is changed for this state of operation. The device itself is protected during all phases of operation in spite of the thermal radiation of the strand material. The structure of the device is simplified because only one chamber is required for the treatment liquid.
In accordance with a further development of the invention, the basic concept of the invention makes it possible that through an increased cooling liquid pressure the switching member can switch off the quantity of cooling liquid necessary for cooling the device.
In accordance with another improvement provided by the invention, a closing or valve member is arranged in a housing in the area of the device cooling liquid outlet in such a way that the closing or valve member is in the flow path of the device cooling liquid and can be actuated by the device cooling liquid. This makes it possible to provide the switching member with the described properties in close vicinity to the nozzle beam. Simultaneously, the nozzle beam becomes very compact, so that no additional space is required.
In accordance with an advantageous feature, the closing or valve member is composed of a conical or spherical body mounted in the housing with guide portions at both ends. The liquid can easily flow around the conical body or the spherical body.
In accordance with another feature, the closing or valve member is adjustable against the force of a compression spring which coaxially surrounds a front guide portion of the closing or valve member. Consequently, the closing or valve member is held open against closing as a result of a restoring force.
The restoring force of the closing or valve member can also be derived from its own weight, either alone or in combination with the compression spring.
In accordance with another development, a cooling liquid discharge pipe is connected in front of and following the closing or valve member in the direction of the flow path of the device cooling liquid to the front guide portion which is surrounded by a liquid space. When the strand material cooling or descaling unit is switched on, the increase of the liquid pressure in the nozzle beam and the resulting increase of the flow velocity produces a pressure drop in the area of the closing or valve member which overcomes the restoring force and presses the closing or valve member in a closed position.
A secure closing action is achieved by arranging a seat ring with a closing edge for the closing or valve member with conical body in the housing at the inlet opening of the device cooling liquid space. The seat ring with closing edge may be of cylindrical or conical construction. The same operation is achieved in the case of a spherical body or partially spherical body as the closing or valve member. When the supply of product treatment liquid is switched off, the reduced pressure in the nozzle beam makes it possible for the restoring force to move the closing or valve member out of the seat ring and to once again open up the device cooling liquid outlet.
The geodetic highest level of the treatment liquid outlet must be selected in such a way that the closing or valve member and the free outlet are arranged below the geodetic level of the product treatment liquid and the overflow pipes thereof. Consequently, the lower portion of the nozzle beam remains filled with device cooling liquid while the overflow for the product treatment liquid at a higher level is not reached, and thus, device cooling liquid does not flow onto the strand material when the supply of product treatment liquid is switched off.
The device cooling liquid is supplied through an adjusting member and/or a check valve in a defined quantity which corresponds to the structural size of the cooling liquid outlet, the required liquid quantity, the structural unit and the operation of the closing or valve member. This makes it possible to take the device cooling liquid from the product treatment liquid supply while bypassing the closed inlet of the product treatment liquid. A check valve is not required in this arrangement. If the device cooling liquid is supplied from a separate supply with a low pressure, the check valve is usually provided in order to lock the flow into the device cooling liquid supply system when the supply of treatment liquid is switched on.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the descriptive matter in which there are described preferred embodiments of the invention.